Studies will continue on a project that contributes to our understanding of the ecology, distribution and control of certain diseases transmitted by fleas, mites, etc., or harbored by rodents. Faunal analyuses are used to predict the presence of diseases like hemorrhagic fever with renal syndrome, tularemia and murine typhus in regions or habitats were such ingections are currently unrecognized. This approach, developed under this Grant, has proven to be highly useful and has led to our demonstration of scrub typhus, tick typhus and other infections in completely unexpected geographic and ecological areas. It has also helped focus on commensal rats living indoors, and their ectoparasites, as critical factors in the ecology of murine typhus. Our newly-advanced hypothesis, namely, that man acquires infections from those mammals that are higher than man in th evolutionary scale (e.g., rodents, carnivorous, unglates), rather than from the lower forms (shrews, marsupials, cold-blooded vertebrates, etc.), may have broad application. Thus, the principle may extend to certain vector of disease like plague or typhys. Data on the zoogeography, host-relationships and phylogeny of ectoparasites and mammals led us to espouse hypotheses deemed radical at the time, viz. continental drift, faunal connections between the southern continents and between North America & Europe. These ideas which have since received substantial support from other fields, e.g. plate tectonics, also help explain important points about the distribution of disease. Their application will be extended. Taxonomic studies will continue to facilitate identification of vectors and analyses of data on their phylogeny, evolution and host-relationships, and will provide background data of value regarding the zoogeography and affinities of rodent and other hosts.